I am working on a R75/5 (1973) that has some /2 and /3 conversion. The gas tank is similar to a /2 or /3 but I don't think it is original style - close. The frame has the /2/3 bolt tabs in the front near the forks. The tank petcock leaks gas and the "U" shape cut near the seat is very poorly done. I would like to replace the tank with a new/ used /2 or /3 tank. Has anyone done this before and if so what challenges did you have? What problems should I Expect? Thanks for the help